<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
     <style>
        .out{
            width: 200px;
            height: 400px;
            margin: 100px auto;
        }


     </style>
</head>
<body>

       <div class='out'>
           <div class='content'></div>
           <div class='input_div'>
               <input type="text" id='msg'>
               <button>发送(增加)</button>
               <button>撤回(删除)</button>
               <button>修改(替换)</button>
            </div>
       </div>
    
</body>
</html>

